PM7347 datasheet(317/341 Pages) PMC

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S/UNI®-JET Data Sheet

Released

Proprietary and Confidential to PMC-Sierra, Inc., and for its Customers’ Internal Use

317

Document ID: PMC-1990267, Issue 3

Figure 73 Multi-PHY Polling and Addressing Transmit Cell Interface

TCA

TSOC

TDAT[15 :0]

TPRTY

W(n-6) W(n-5)

W(n-4) W(n-3) W(n-2) W(n-1) W(n)

W(n-7)

TFCLK

TENB

TADR[2:0]

CA(A)

CA(B)

CA(C)

CA(B)

1Fh

CA(A)

DTCA[D]

TCALE VEL 0=0

Figure 73 is an example of the multi-PHY polling and selection sequence supported by the

S/UNI-JET . "A", "B", "C", and “D” represent any arbitrary address values of PHY devices which

may be occupied by the S/UNI-JET . The ATM Layer device is not restricted in its polling order.

Initially PHY “D” is accepting a cell and the direct TCA for that PHY is shown as DTCA[D]. The

effect of TCALEVEL0 is indicated with a dashed line in the figure. The PHY associated with

address "A" indicates it cannot accept a cell, but PHY "B" indicates it is willing to accept a cell.

As a result, the ATM Layer places address "B" on TADR[2:0] the cycle before TENB is asserted

to select PHY "B" as the next cell destination. In this example, the PHY "C" status is ignored. The

ATM Layer device is not constrained to select the latest PHY polled. As soon as the cell transfer

is started, the polling process may be restarted. The data on TDATI (W1, W2, ..) may be 8-bit or

16-bits wide, depending on the setting of the ATM8 input.

During multi-PHY operation, several PHY layer devices share the TCA signal. As a result, this

signals must be tri-stated in all PHY devices which have not been selected for polling by the ATM

Layer. The value of TADR[2:0] selects the PHY being polled for the TCA signal, and all devices

not corresponding to this address must tri-state its TCA output. This multi-PHY operation is

directly supported by the S/UNI-JET .

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